This application relates generally to the field of medical apparatuses known as maxillomandibular fixation (MMF) devices, and more particularly to such MMF devices comprising arch bars adapted for fixation to the maxilla or mandible of a patient, each arch bar having hooks, buttons or similar projections, whereby the a pair of arch bars are connected to each other, typically by wire wrapped around and extending between opposing hooks, so as to secure the upper and lower jaws in a closed position.
In some procedures, the MMF arch bars are attached to the teeth using encircling wires. In other procedures, the MMF arch bars are affixed to maxillary or mandibular bone tissue by mechanical fasteners, e.g., bone screws. It is important in these circumstances that the bones screws do not impinge on the roots of the teeth. Early embodiments for such MMF arch bars utilized screw-receiving apertures that were fixed in spaced position along the arch bar, which often resulted in circumstances wherein certain apertures were not available for use because of their location over a tooth root. Later embodiments addressed this by providing apertures on malleable stems such that the location of the aperture could be shifted by bending the stem. Bending stems to adjust the aperture location results in undesirable curvatures out-of-plane and weakens the security of the arch bars once the arch wires are tightened to close the jaw. Other embodiments provide the mounting apertures on mounting assemblies that can be moved along the arch bar and then mechanically fastened to the arch bar by a set screw for example. A problem with this structure is the possibility that the fastening elements may loosen over time.
It is an object of this invention to provide an MMF device that allows for movement or relocation of mounting plate members comprising the screw-receiving apertures along the arch bar to avoid tooth roots, without sacrificing rigidity, strength and fixation.